Refactor where store drivers are initialized

The call to create_stores was happening in the v1 and v2 API
controllers. This moves that call and the verification that
the default_store exists into the necessary binaries.

Fixes bug 1039727.

Change-Id: I36542fd9b1d536d6266898766317abe110bb71a2

glance/store/__init__.py

@@ -21,6 +21,7 @@ import time
 
 from glance.common import exception
 from glance.common import utils
+import glance.context
 from glance.openstack.common import cfg
 from glance.openstack.common import importutils
 import glance.openstack.common.log as logging
@@ -37,6 +38,10 @@ store_opts = [
                     'glance.store.s3.Store',
                     'glance.store.swift.Store',
                 ]),
+    cfg.StrOpt('default_store', default='file',
+               help=_("Default scheme to use to store image data. The "
+                      "scheme must be registered by one of the stores "
+                      "defined by the 'known_stores' config option.")),
     cfg.StrOpt('scrubber_datadir',
                default='/var/lib/glance/scrubber'),
     cfg.BoolOpt('delayed_delete', default=False),
@@ -168,6 +173,16 @@ def create_stores():
     return store_count
 
 
+def verify_default_store():
+    scheme = cfg.CONF.default_store
+    context = glance.context.RequestContext()
+    try:
+        get_store_from_scheme(context, scheme)
+    except exception.UnknownScheme:
+        msg = _("Store for scheme %s not found") % scheme
+        raise RuntimeError(msg)
+
+
 def get_store_from_scheme(context, scheme):
     """
     Given a scheme, return the appropriate store object

glance/store/scrubber.py

@@ -92,8 +92,6 @@ class Scrubber(object):
 
         utils.safe_mkdirs(self.datadir)
 
-        store.create_stores()
-
     def run(self, pool, event=None):
         now = time.time()